[JENKINS-57383] add missing cast (#4104)

(cherry picked from commit 9769092e)

core/src/main/java/hudson/ProxyConfiguration.java

@@ -396,7 +396,7 @@ public final class ProxyConfiguration extends AbstractDescribableImpl<ProxyConfi
             GetMethod method = null;
             try {
                 method = new GetMethod(testUrl);
-                method.getParams().setParameter("http.socket.timeout", DEFAULT_CONNECT_TIMEOUT_MILLIS > 0 ? DEFAULT_CONNECT_TIMEOUT_MILLIS : TimeUnit.SECONDS.toMillis(30));
+                method.getParams().setParameter("http.socket.timeout", DEFAULT_CONNECT_TIMEOUT_MILLIS > 0 ? DEFAULT_CONNECT_TIMEOUT_MILLIS : (int)TimeUnit.SECONDS.toMillis(30));
                 
                 HttpClient client = new HttpClient();
                 if (Util.fixEmptyAndTrim(name) != null && !isNoProxyHost(host, noProxyHost)) {